block/blk-lib.c

   1 /*
   2  * Functions related to generic helpers functions
   3  */
   4 #include <linux/kernel.h>
   5 #include <linux/module.h>
   6 #include <linux/bio.h>
   7 #include <linux/blkdev.h>
   8 #include <linux/scatterlist.h>
   9
  10 #include "blk.h"
  11
  12 struct bio_batch {
  13         atomic_t                done;
  14         unsigned long           flags;
  15         struct completion       *wait;
  16 };
  17
  18 static void bio_batch_end_io(struct bio *bio, int err)
  19 {
  20         struct bio_batch *bb = bio->bi_private;
  21
  22         if (err && (err != -EOPNOTSUPP))
  23                 clear_bit(BIO_UPTODATE, &bb->flags);
  24         if (atomic_dec_and_test(&bb->done))
  25                 complete(bb->wait);
  26         bio_put(bio);
  27 }
  28
  29 /**
  30  * blkdev_issue_discard - queue a discard
  31  * @bdev:       blockdev to issue discard for
  32  * @sector:     start sector
  33  * @nr_sects:   number of sectors to discard
  34  * @gfp_mask:   memory allocation flags (for bio_alloc)
  35  * @flags:      BLKDEV_IFL_* flags to control behaviour
  36  *
  37  * Description:
  38  *    Issue a discard request for the sectors in question.
  39  */
  40 int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
  41                 sector_t nr_sects, gfp_t gfp_mask, unsigned long flags)
  42 {
  43         DECLARE_COMPLETION_ONSTACK(wait);
  44         struct request_queue *q = bdev_get_queue(bdev);
  45         int type = REQ_WRITE | REQ_DISCARD;
  46         unsigned int max_discard_sectors;
  47         unsigned int granularity, alignment, mask;
  48         struct bio_batch bb;
  49         struct bio *bio;
  50         int ret = 0;
  51
  52         if (!q)
  53                 return -ENXIO;
  54
  55         if (!blk_queue_discard(q))
  56                 return -EOPNOTSUPP;
  57
  58         /* Zero-sector (unknown) and one-sector granularities are the same.  */
  59         granularity = max(q->limits.discard_granularity >> 9, 1U);
  60         mask = granularity - 1;
  61         alignment = (bdev_discard_alignment(bdev) >> 9) & mask;
  62
  63         /*
  64          * Ensure that max_discard_sectors is of the proper
  65          * granularity, so that requests stay aligned after a split.
  66          */
  67         max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9);
  68         max_discard_sectors = round_down(max_discard_sectors, granularity);
  69         if (unlikely(!max_discard_sectors)) {
  70                 /* Avoid infinite loop below. Being cautious never hurts. */
  71                 return -EOPNOTSUPP;
  72         }
  73
  74         if (flags & BLKDEV_DISCARD_SECURE) {
  75                 if (!blk_queue_secdiscard(q))
  76                         return -EOPNOTSUPP;
  77                 type |= REQ_SECURE;
  78         }
  79
  80         atomic_set(&bb.done, 1);
  81         bb.flags = 1 << BIO_UPTODATE;
  82         bb.wait = &wait;
  83
  84         while (nr_sects) {
  85                 unsigned int req_sects;
  86                 sector_t end_sect;
  87
  88                 bio = bio_alloc(gfp_mask, 1);
  89                 if (!bio) {
  90                         ret = -ENOMEM;
  91                         break;
  92                 }
  93
  94                 req_sects = min_t(sector_t, nr_sects, max_discard_sectors);
  95
  96                 /*
  97                  * If splitting a request, and the next starting sector would be
  98                  * misaligned, stop the discard at the previous aligned sector.
  99                  */
 100                 end_sect = sector + req_sects;
 101                 if (req_sects < nr_sects && (end_sect & mask) != alignment) {
 102                         end_sect =
 103                                 round_down(end_sect - alignment, granularity)
 104                                 + alignment;
 105                         req_sects = end_sect - sector;
 106                 }
 107
 108                 bio->bi_sector = sector;
 109                 bio->bi_end_io = bio_batch_end_io;
 110                 bio->bi_bdev = bdev;
 111                 bio->bi_private = &bb;
 112
 113                 bio->bi_size = req_sects << 9;
 114                 nr_sects -= req_sects;
 115                 sector = end_sect;
 116
 117                 atomic_inc(&bb.done);
 118                 submit_bio(type, bio);
 119         }
 120
 121         /* Wait for bios in-flight */
 122         if (!atomic_dec_and_test(&bb.done))
 123                 wait_for_completion(&wait);
 124
 125         if (!test_bit(BIO_UPTODATE, &bb.flags))
 126                 ret = -EIO;
 127
 128         return ret;
 129 }
 130 EXPORT_SYMBOL(blkdev_issue_discard);
 131
 132 /**
 133  * blkdev_issue_zeroout - generate number of zero filed write bios
 134  * @bdev:       blockdev to issue
 135  * @sector:     start sector
 136  * @nr_sects:   number of sectors to write
 137  * @gfp_mask:   memory allocation flags (for bio_alloc)
 138  *
 139  * Description:
 140  *  Generate and issue number of bios with zerofiled pages.
 141  */
 142
 143 int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
 144                         sector_t nr_sects, gfp_t gfp_mask)
 145 {
 146         int ret;
 147         struct bio *bio;
 148         struct bio_batch bb;
 149         unsigned int sz;
 150         DECLARE_COMPLETION_ONSTACK(wait);
 151
 152         atomic_set(&bb.done, 1);
 153         bb.flags = 1 << BIO_UPTODATE;
 154         bb.wait = &wait;
 155
 156         ret = 0;
 157         while (nr_sects != 0) {
 158                 bio = bio_alloc(gfp_mask,
 159                                 min(nr_sects, (sector_t)BIO_MAX_PAGES));
 160                 if (!bio) {
 161                         ret = -ENOMEM;
 162                         break;
 163                 }
 164
 165                 bio->bi_sector = sector;
 166                 bio->bi_bdev   = bdev;
 167                 bio->bi_end_io = bio_batch_end_io;
 168                 bio->bi_private = &bb;
 169
 170                 while (nr_sects != 0) {
 171                         sz = min((sector_t) PAGE_SIZE >> 9 , nr_sects);
 172                         ret = bio_add_page(bio, ZERO_PAGE(0), sz << 9, 0);
 173                         nr_sects -= ret >> 9;
 174                         sector += ret >> 9;
 175                         if (ret < (sz << 9))
 176                                 break;
 177                 }
 178                 ret = 0;
 179                 atomic_inc(&bb.done);
 180                 submit_bio(WRITE, bio);
 181         }
 182
 183         /* Wait for bios in-flight */
 184         if (!atomic_dec_and_test(&bb.done))
 185                 wait_for_completion(&wait);
 186
 187         if (!test_bit(BIO_UPTODATE, &bb.flags))
 188                 /* One of bios in the batch was completed with error.*/
 189                 ret = -EIO;
 190
 191         return ret;
 192 }
 193 EXPORT_SYMBOL(blkdev_issue_zeroout);